Typically, a number of components are mounted on a circuit board. When power is supplied, the components operate and produce heat. If the generated heat is not radiated, the components are subject to the malfunction and the damage due to the heat. Particularly, light emitting components such as LED, which produce a great deal of heat than other components, are subject to the severe heat damage compared to other components.
FIG. 1 is a cross section view of a conventional circuit board having an LED, and FIG. 2 is a plane view of the circuit board of FIG. 1.
The circuit board includes an insulating substrate 4, and conductive patterns 8 and 9 which are formed in upper and lower sides (hereafter, referred to as both sides). The circuit board has through holes where the LED is mounted. Eyelets 5 and 6 in sleeve shape are disposed in the through holes.
The LED mounted in the circuit board includes an LED body 1, and a pair of lead pins 2 and 3 protruding below the LED body 1. The lead pins 2 and 3 are mounted through the through holes of the circuit board and electrically connected to the conductive patterns by means of soldering. Power is supplied to the LED mounted in the circuit board through the conductive patterns 8 and 9, to thus turn on the LED and emit the light.
As radiating, the LED produces a great deal of heat. Thus, if the heat is not exhausted to outside, the heat may attenuate the brightness of the LED and shorten the life span of the LED.
To prevent the malfunction and the lifespan reduction of the components mounted in the circuit board, the heat produced by the components should be dissipated. In particular, a radiating structure is essential to the heat producing component such as LED.
To respond to this, the conventional methods mostly radiate the heat to outside by mounting a separate heat sink on the circuit board. However, the radiation effect does not meet the expectations because the heat is not effectively radiated merely by mounting the heat sink.